By 1850, the Union had grown to 31 states, and the Capitol was too small to accommodate all newly elected senators and representatives. An expansion of the building continued steadily through the troubled times of the next decade. The completion of the majestic Capitol Dome in 1863, in the midst of the war, symbolized northern resolve to preserve the Union.

July 4, 1851: Cornerstone Laid for Capitol Expansion

While the nation’s expansion intensified the slavery debate, the increasing number of representatives and senators outgrew congressional chambers. In 1850, architects submitted designs for an expansion. The Senate and House could not agree on how to best expand the Capitol, so the decision was left to President Millard Fillmore. As a compromise, he chose the architect favored by the House, Thomas U. Walter of Philadelphia, and the plans favored by the Senate. The cornerstone was laid on July 4, 1851, beginning 17 years of construction that included new House and Senate wings, the iconic Dome and additional improvements.

Captain Montgomery Meigs of the U.S. army Corps of Engineers oversaw the construction of the Capitol extension, including the House and Senate wings and the Dome. He hired artist Constantino Brumidi to design and paint murals, including frescoes for the interior spaces. Meigs commissioned sculptor Thomas Crawford to design the Statue of Freedom for the top of the Dome.

Before the Civil War, Italian immigrant Constantino Brumidi worked with teams of artists to create colorful murals on the Capitol walls. His murals celebrated nature and classical themes, as well as American history, values and ingenuity. He continued to paint frescoes in the Capitol during and after the Civil War.

In 1855 Congress voted to replace the old Dome with a fireproof cast-iron Dome designed by Thomas U. Walter. When workers removed the old Dome in 1856, they built a temporary roof over the Rotunda. Steam-powered derricks lifted the new Dome’s cast-iron pieces into place. Contractors continued construction during the war, despite being warned not to expect payment. Many saw this as a sign that the Union would also continue. The 9-million-pound Dome was topped on December 2, 1863, with the Statue of Freedom, and completed in January 1866.

The House of Representatives moved into its new chamber on December 16, 1857, while the Senate first occupied its new chamber on January 4, 1859. The enlarged chambers featured wrought iron and glass ceilings and improved heating and ventilating systems. Though enlarged to accommodate a rapidly growing Union, the secession of 11 states in 1860 and 1861 left many seats empty.

The 19 ½ -foot Statue of Freedom was raised to the top of the Capitol Dome in five main sections and then assembled. The final section was raised on December 2, 1863, accompanied by a 35-gun salute. By then Philip Reid, who worked as a slave on the statue, was a free man. During the statue’s casting, Reid solved the problem of how to separate the plaster model into five sections that could be cast in bronze and reassembled into one seamless statue representing freedom and unity. The motto on its pedestal read “E Pluribus Unum,” which means “Out of Many, One.”

In 1864, even before the end of the Civil War, Congress passed legislation that invited every state to contribute two statues to be placed in the old House Chamber, renamed National Statuary Hall. The statues of deceased citizens known for “their historic renown or for distinguished civic or military services” eventually included those who had served during the Civil War on both sides as soldiers, generals and politicians. In 1870, the statue of Revolutionary War hero Nathaniel Greene of Rhode Island became the first to arrive.

Painted on the Capitol Rotunda’s canopy at the end of the Civil War, The Apotheosis of Washington fresco features George Washington rising to the heavens surrounded by female figures representing liberty/authority and victory/fame and the original 13 colonies. Paintings around the perimeter include scenes of War, Science, Marine, Commerce, Mechanics and Agriculture - subjects chosen to highlight American achievements.